Error LNK2020 in C++/CLI

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C++/CLI

Hello every body !

1st my E.L not good, i write i think ! :)

now,
I need help, i was try to fix but not work ! it build in flatform C++/CLI

it's have wrong
this is error , details below

error LNK2020: unresolved token (06000001)
error LNK2020: unresolved token (06000002)
error LNK2020: unresolved token (06000002)

details

in stdafx.h

<pre lang="c++">
#pragma once
using namespace System;
using namespace System::Data;
using namespace System::Data::SqlClient;
using namespace System::Collections::Generic;

in SQLservices

<pre lang="c++">#pragma once
#include "stdafx.h"


ref class SQLservices
{


	//variable
private:

	String^ hostserver;	
	String^ dataname;
	static SqlConnection^ sqlcon = gcnew SqlConnection;

	//destroy
protected:
	~SQLservices();

public:

	
	//property
	property String^ HostServer{
		String^ get(){ return hostserver; }
		void	set(String^ value){ hostserver	= value;}
	};

	property String^ DataName{
	        String^ get(){ return dataname;	}
		void	set(String^ value){ dataname= value;}
	}


	//constructor
	SQLservices(void);
	SQLservices(String^ HostServer,String ^DataName);
	

	//method

	Boolean^ checkConnection();
	Boolean^ getStateConnection();
	void closeConnection();
};

in in SQLservices.cpp

#include "stdafx.h"
#include "SQLservices.h"


SQLservices::SQLservices(void){}

SQLservices::SQLservices(String^ mHostServer,String^ mDataName){
	this->HostServer = mHostServer;
	this->DataName= mDataName;
}

SQLservices::~SQLservices(){}

System::Boolean^ SQLservices::checkConnection(){
	sqlcon->ConnectionString = "Data source = " + this->hostserver + ";Initial Catalog = " + this->dataname + ";Integrated Security=True; Pooling = false; MultipleActiveResultSets=True; TrustServerCertificate=False; User Instance=False"; 
	try{
		sqlcon->Open();
		return true;
	}
	catch (...){
		return false;
	}
}

System::Boolean^ SQLservices::getStateConnection(){ return (sqlcon->State == ConnectionState::Open) ? true :false ; }

System::Void SQLservices::closeConnection(){
	try{
		sqlcon->Close();
	}
	catch(...){/*nothing to do */}
}

in class Form1.h i using class SQLservices

#include "SQLservicer.h"

//declare class SQLservices
SQLservicer^ SQLTools;

//using SQLTools in btnTestConnection  in event Click
String^ host = gcnew String(tbxHostServer->Text);
String^ data = gcnew String(tbxDataName->Text);

SQLTools = gcnew SQLservicer(host,data);

if(SQLTools->CheckConnectionSQL()) {...}

and now here is error

<pre lang="c++">Error	1	error LNK2020: unresolved token (06000001) BaiTapNhom_ADO.SQLservicer::.ctor	D:\Studing\Solution\VisualCPlusplus\Work_ADO\Work_ADO\Work_ADO.obj	Work_ADO
Error	2	error LNK2020: unresolved token (06000002) BaiTapNhom_ADO.SQLservicer::CheckConnectionSQL	D:\Studing\Solution\VisualCPlusplus\Work_ADO\Work_ADO\Work_ADO.obj	Work_ADO
Error	3	error LNK2020: unresolved token (06000003) BaiTapNhom_ADO.SQLservicer::~SQLservicer	D:\Studing\Solution\VisualCPlusplus\Work_ADO\Work_ADO\Work_ADO.obj	Work_ADO
Error	4	error LNK1120: 3 unresolved externals	D:\Studing\Solution\VisualCPlusplus\Work_ADO\Debug\Work_ADO.exe	Work_ADO